The embodiments disclosed herein relate to methods, systems, and system components for creating and arranging small (micron and smaller) defects or perforations in transparent materials in a particular manner, and, more particularly, to the arrangement of these defects, each of which has an average crack length, in a predetermined spaced-apart relation (each defect separated from an adjacent defect by a predetermined distance) defining a contour in a transparent material to lower the relative interface fracture toughness for subsequent planned induced separation.
In recent years, precision micromachining and related process improvements to meet customer demands to reduce the size, weight and material cost of leading-edge devices has led to fast pace growth in high-tech industries in flat panel displays for touch screens, tablets, smartphones and televisions. Moreover, ultrafast industrial lasers are becoming important tools for applications requiring high precision micromachining.
Relatively large glass sheets/substrates are typically delivered to manufacturers; and thus, they need to be cut into smaller sizes before being further processed. (Such processing may include additional layers of coating, thin film transistors (“TFTs”) or other value adding attributes of the glass surface. In many conventional laser glass cutting processes, the separation of glass into smaller sheets relies on laser scribing or perforation followed by separation with mechanical force or thermal stress-induced crack propagation. Nearly all current laser cutting techniques exhibit one or more shortcomings, including: (1) limitations in their ability to perform a free form shaped cut of thin glass on a carrier due to a large heat-affected zone associated with the long laser pulses (nanosecond scale or longer) used for cutting; (2) production of thermal stress that often results in cracking of the glass surface near the region of laser illumination due to the generation of shock waves and uncontrolled material removal; (3) difficulties in controlling the depth of the cut (e.g., to within tens of microns); and/or (4) creation of sub-surface damage in the glass that extends hundreds of microns (or more) glass below the surface of the glass, resulting in defect sites at which crack propagation can initiate.
Some glasses are easily separated with conventional tools such as mechanical cutting equipment, or CO2 laser cutting processes. Some glasses are difficult to cut using these techniques, and more complicated and sophisticated equipment may be needed. For example, mechanically or chemically strengthened glasses are difficult to cut using the aforementioned mechanical tools or CO2 lasers. Thin glasses (<0.2 mm thick) are another example of glasses that are difficult to cut using conventional equipment. Glass-ceramics and other transparent materials characterized by a high fracture toughness are also difficult to separate using conventional mechanical tools. Accordingly, there is a need to address the aforementioned issues and provide improved glass separation equipment and techniques.